Spectrophotometric study on the charge-transfer reaction between 4-aminopyridine with 2,5-dihydroxy-p-benzoquinone in methanol and the binary mixture 50% acetonitrile + 50% 1,4-dioxane (v/v)

摘要

Charge-transfer (CT) reaction between 4-aminopyridine (4APy) as the electron donor with 2,5-dihydroxy-p-benzoquinone (DHBQ) as the electron acceptor has been investigated spectrophotometrically in methanol (MeOH) and a binary mixture composed of 50% acetonitrile and 50% 1,4-dioxane (v/v) (ANDI). The composition of the complex has been investigated utilising Job's and photometric titration methods to be 1:1. Benesi-Hildebrand equation has been applied to estimate the formation constant of the CT reaction (K CT) and the molecular extinction coefficient (ε{lunate}) where they reached high values confirming high stability of the produced complex. The solid CT complex (4APy-DHBQ) was isolated, and elemental analysis proved its formation in 1:1 ratio. A spectral study on the formed complex has been carried out using infrared and 1H NMR measurements, where it included hydrogen bonding beside CT.